Look at the lists linked to in the section called “Selective lists”:
These are lists of books generally considered good. If you explore further by clicking on the links and clicking on the links within the linked pages, you’ll find some more lists. For instance, here’s another list:
http://en.wikipedia.org/wiki/All-Time_100_Greatest_Novels
And here’s one:
Nancy Pearl’s Book Lust. You know you can trust her- she’s the model for the Librarian Action Figure with Deluxe Shushing Action. There’s a wiki, weekly suggestions on KUOW (a Seattle public radio station), and several books of reviews.
Can I just explain something - The websites or magazines that recommend books don’t know Lobsang’s tastes. This is why I deliberately left them out.
ETA: In fact, if anything, listing my tastes would have actually detracted from what I wanted: Someone might have looked at my tastes and thought “Oh he won’t like this, it’s not X” where I might have actually loved the book you thought of recommending. I like good books.
But for the sake of it here are my tastes…
Science fiction. (Discworld, Asimov, etc…)
Science fact. (Ghost Map being an example of that)
Thrillers if well written (there are too many of them out there so I’m turned off the usual serialized stuff my relatives read)
Fantasy (OK I like Harry Potter. Give me a break - lot’s do. Neil Gaiman)
Difficult to place - David Mitchell.
And more importantly Just about any good book. If a book is well written then it transcends my ‘tastes’.
I apologise for being snarky to people.
Your OP says you want a source that recommends good books. There’s no source that will recommend only what fits your taste, but there are sources that recommend good books. You’ll have to take it from there, look at the books they recommend, and see what sounds good to you.
My recommendation for Bookmarks magazine still stands. They review books in all the categories you like. You’ll be able to read what the book’s about, and you’ll see what the critics and reviewers have to say about it. I’m pretty sure that’s where I heard about Ghost Map.
Or do what I do. Somebody recommends a book that sounds good, I go to Amazon, read the description, and look inside the book. I can usually tell by the first couple of pages if it’s something I’ll like. Also at Amazon you can use the "People who bought — also bought — ". I’ve found a lot of good books that way. Start with David Mitchell – see what else his readers are reading.
Nobody’s gonna say “Here Lobsang, you’re sure to like this.” (Except for English Passengers, of course.) 
You might check the recommendations in The Economist. I don’t think they recommend any junk. It’s mostly nonfiction, but also includes the occasional work of fiction, and thrillers are not uncommon for the fiction selections.
The Spectator, whose demographic isn’t all that different, also has some good recommendations.
In all seriousness, I don’t think you’ll find one source that will consistently recommend books you like – people’s tastes are too widely varied, and the most you’ll probably agree with any source is probably only 70% of the time or so, tops.
That said, aldaily.com has a link to a new book review every day, and I’ve discovered some great books that way. However, your tastes appear to tend towards Fantasy/Sci-Fi, and not many of those books get reviewed on that site.
It’ll sound obvious, but Amazon.com is a great source. Type in the name of a book you like and check on the side panel to see what Listmania lists it shows up on. Click on one of those lists, and you’ll likely find a list of some other books you like, as well as some that are unknown for you, but will probably be just what you’re looking for. The reviews on Amazon are also very handy – in many cases, I’d say the star ratings are actually fairly accurate.
I love goodreads as a database and a way to see what my friends are reading, but I don’t find it very useful for recommendations. Not only does it not offer up books it thinks you would like, it doesn’t even tell you what other users are the best match for you so you can make new book friends. You could click on your own books, one by one, and see who else has given them good reviews, but that’s quite a tedious process!
The Guardian’s Book Review section on Saturday’s has some great recommendations. There’s the added bonus that it’s usually a good read in and of itself.